A retinal display beams light directly onto a viewing surface of an eye as pixels that form an image. The retinal display produces a brighter, higher resolution image than previous cathode-ray or liquid crystal displays. Head mounted display applications of retinal displays are suitable for consumer virtual reality viewer applications. For a full virtual reality effect, the head mounted display should project onto an undistorted visual field that fills the user's field of view. With a head mounted display, the source display is positioned relatively close to the eye in order for the head mounted display to be compact. However, close proximity to the eye is normally a problem in that the human eye cannot see a very closely positioned image unless it is focused with a lens.
A conventional lens system, as shown by the diagram 1 in FIG. 1, presents a planar display through a right lens 11 to the right eye 14 and through a left lens 11' to the left eye 14'. The traditional single stage optic lenses, 11 and 11', severely limit the horizontal field of views 12 and 13 for each eye to, typically, 30 degrees. As a result, the total viewing field 16 is limited to 30 degrees. As the display size is directly proportional to the angular incidence, it becomes increasingly more difficult for the eye to resolve images which occupy much more than 30 degrees of the visual field 16. Consequently, as shown by the diagram 1 in FIG. 1B, the stereo aperture 15 in relation to the combined left and right viewing fields 12 and 13 is farther out from the retinal surfaces of the eyes 14 and 14'. These single type optical solutions to the problem of wide-field image presentation lead to problems of spherical distortion, chromatic shift, and focus, as the distance to the eye from the center of the image plane increase.
In designing remote vision systems for human operators, two different aspects of human vision should be considered: the high central (foveal) acuity of the eye, and the combined peripheral field of view which accounts for 90% of orientation in three dimensional space. In addition, when creating a commercially viable product of this type, several other engineering factors must be considered including: wearer comfort, versatility and contemporary design.
Accordingly there is a need for an optical system that is capable of converting images from a small electronic source display onto an undistorted visual plane that can fill a viewer's visual field.